Estimative language and confidence levels: saying exactly what you mean
Estimative language assigns numeric probability bands to standard phrases — very unlikely 5-20%, unlikely 20-40%, roughly even chance 40-60%, likely 60-80%, very likely 80-95%, almost certain 95-99% — while confidence levels (high, moderate, low) describe the strength of the underlying sourcing and reasoning. The two are always stated separately.
Two readers given the word "probable" will act on very different odds. Calibrated language removes that variance at zero cost.
- Publish the probability yardstick alongside the assessment so readers share the scale.
- One probability term per judgement — never stack hedges.
- Confidence is about evidence quality; likelihood is about the world.
- Justify confidence in one sentence: corroboration, access, recency or assumptions.
- Flag every change from a previous judgement explicitly.
The probability yardstick
Fix the bands once and use them everywhere:
- Almost no chance — 1-5%
- Very unlikely — 5-20%
- Unlikely — 20-40%
- Roughly even chance — 40-60%
- Likely / probable — 60-80%
- Very likely — 80-95%
- Almost certain — 95-99%
Confidence levels and their drivers
High confidence rests on multiple independent, well-placed sources with consistent reporting and few load-bearing assumptions. Moderate confidence typically means credible sourcing with gaps or limited corroboration. Low confidence means fragmentary, uncorroborated or dated information, or heavy assumption dependence — which does not prevent a judgement, it qualifies it.
Writing the judgement line
A complete judgement contains outcome, probability, timeframe, confidence and driver: "Localised disruption to the north approach is likely (60-80%) during the 18:00-20:00 arrival window; moderate confidence, based on two independent mobilisation posts and the last edition's pattern."
Consistency and change notes
Analytic standards require consistency over time: when a judgement moves, say what moved it. "Raised from unlikely to likely following confirmed permit issuance" preserves trust far better than a silently rewritten paragraph.
Frequently asked questions
- What does 'likely' mean in intelligence reporting?
- In standard estimative usage, 'likely' or 'probable' means a 60-80% chance that the outcome occurs within the stated timeframe. The term should always appear with a timeframe and a separate confidence level.
- Can a judgement be very likely with low confidence?
- Yes. Likelihood estimates the outcome; confidence rates the evidence. A single credible but uncorroborated report can justify a high-probability judgement held with low confidence, which tells the decision-maker to plan for it and keep collecting.
Apply this to your next event
Preventio turns event details into a structured intelligence brief with OSINT review, threat matrix, crowd analysis and operational recommendations.
Related guides
The correct intelligence analysis methodology, step by step: requirements, collection, source evaluation, structured analytic techniques, estimative language, confidence levels and BLUF reporting.
How to run analysis of competing hypotheses in event security: build the hypothesis set, score evidence for diagnosticity, eliminate on inconsistency and report the surviving judgement.
A structured methodology for event threat assessment: scenario framing, likelihood and impact scoring, vulnerability analysis and a defensible overall risk rating.